Furnace conveyer shaft with disks



Aug. 23, 1932. F, A4,. FAHRENWALD 1,872,711

FURNACE CONVEYER SHAFT WITH DISKS Filed Sept. 29. 1930 3 Sheets-Sheet l Aug. 23, 1932. F. A. FAHRENWALD FURNACE CQNVEYER SHAFT WIIH DISKS Filed Sept. 29, 1930 5 Sheets-Sheet 2 f Al1g 23, 1932 F. A. FAHRENWALD v 1,872,711

FURNACE CONVEYER SHAFT WITH DISKS Filer; sept. 29, 1930 5 sheets-sheet 5 f f M Patented Aug. 23, 1932 entren STATES FRANK A. YE AHRENWALLD, CHICAGQ, ILLENOIS FURNACE coNvnY-Ea snAFr WITH Disks Appui-.ation inea september 2e, 1930. semi no. essere.

This invention relates `to a novel construction of shaft for use in heat treatment furnaces, for instance, sheet steel normalizing furnaces, and particularly a shaft upon Which are mounted Work supporting disks or the like. The invention also relates to a novel construction yof means whereby the disks are held `in assembly With and receive their drive from the shaft. The invention alsorelates to a novel combination of shaft' and disks which avoids deteriorating stresses in the members under heat expansion; also to a novel combinationof shaft disk and interlocking means whereby the disks are posil tioned upon the shaft and driven bythe shaft.

Among the problems to be met in provid,- ing and maintaining in operative condition the vwork supporting and feeding shaft in a heat treatment furnace are the establishment i of a relation of structural strength to Weight sustained in the shaft that-Will avoid distortion or letting down of the portion of the shaft Within the high temperature area' of s the furnace, While the shaft is being supported by its ends in bearings located outside the Walls of the furnace; the avoidance of checking or cracking of the shaft underV heat expansion; the avoidance of undue cooling of the furnace chamber andthe i sheets or other Workpieces by conduction of heat through the Work supporting disks and the shaft; the provision for convenient assemblyof the disks with and in driven Vrelation to the shaft aswell as their ready disl of production of shafts for the purpose stated, it is also desirable to havea construetion of shaft Which will facilitate coring, proper distribution of the metal in pouring,

avoidance of checking and crackingin cooling, and facility for dressing and thereby providing accurate alignment of disk-seats upon the shaft without having to straighten the shaft or dress its surface as a Whole, in

insuring a level sheet support across the tops of vall the disks when in use.

and replacement When necessary;

Accordnglyythe present invention contemplates a Yshaft for metallurgical furnaces, or the combinationof'such a shaft and Worksupporting disks surrounding and held lin driving relation upon the shaft, embodying individually,collectively, or in variouscombinations, as hereinafter pointed out in the clai1ns,"structural characteristics substantially as follows. A relatively large holl'ovv bodyT portion With comparatively thin Walls, mad-e ofan alloy which bestovvs upon `the shaft capacity to retain its shape lWhen supported by its .ends (preferably of relatively smaller diameter) 'resting in bearings outside ofthe furnace and While theenlarged portion of the shaftis subjected 'to temperatures of theorder of 1800 to 2000"' F. Withoutthe assistance of cooling influences such as' air or- Water flowing through the shaft; this shaft being constructed With a series of axially spaced seats upon which to mount surrounding Work-supporting disks, each seat. consisting. of a series of circumferentially spaced elevations on the surface ofthe shaft, so thatin insuring coaxial alignment` of the disks upon the shaft, correction of unavoidable distortion inthe cylindrical casting Will involve merely the dressingy (e. g. by grinding) of the faces of the elevations rather than correcting the Whole surfaceof the shaft,-and so that the diskvvheninposition may, if desired, remain out of contact with substantial areas of the shaft between its surface elevations; the elevations upon which the disks Vseat constituting means through which' the shaft drives the disks, to which end, provision'is made for interlocking each disk With one or more of the elevations in; the direction of drive; theinterlocking means being also made to serve, if desired, as-the means'for. preventing displacement of the .disk from its seat and being preferably made conveniently releasable to permit replacement of disks gthe elevations being developed by deflection ofthe Wall of the shaft Without materially changing lthe thickness of the metal at an elevation, as distinguished from developing elevations or protuberanc'es by local enlargement of the mass or :thickness of thevvalhand these elevations, or somelo'f them, being slotted in the direction of the axis of the shaft as a safeguard against setting up strains under high heat expansion; and the several elements of the combination embodying structural details which adapt them to advantageously enter into the functional and cooperative relationships described.

In the accompanying drawings- Figure 1 is a vertical section of a conventional type of heat treating furnace, with a shaft constructed and equipped with disks in accordance with the present invention; disks located by another shaft in rear of the shaft shown being illustrated in positions alternating with the disks on the shaft shown.

Figure 2 is a horizontal section through portions ofthe two side walls ofthe furnace shown in Figure 1, in the plane of the shaft, and showing in axial sections two'adjacent shafts together with disks mounted thereon.

Figure 3 shows in side elevation one of the disksemployed in Figures 1 and 2, and in transverse section in the plane of the disk, theshaft upon which the disk is mounted together with one form of interlocking and driving connection between the disk and the shaft.

Figure 4 shows a shaft in section as in Figure 3, together with a fragmentary portion of the disk, and a modified construction of interlocking and driving means.

Figure 5 is a section on the line of Figure 3, showing the means for interlocking the disk with and imparting its drive from the shaft.

F igurt 6 is an axial section of a portion of a shaft and disks mounted thereon through means of iraised seats upon-the shaft, and a modified construction of releasable bayonet joint. A

Figure 7 is a transverse section on the line 7a3-7m of Figure 6;

Figure 8 is an axial section of a portion of a shaft and disks mounted thereon, showing still another means for interlocking the disks againstdisplacement and transmit-ting their drive from the shaft; and

Figure 9 is a section on the line 9x-9 of Figure 8.

In Figures 1 and 2, A, B and C represent side, bottom and top walls typical of a known construction ofheat treating furnace. 1 represents shafts mounted so that their main body portions will rotate within the furnace, for instance, by having their reduced ends extending through the furnace walls and lsupported in bearings external thereto. 2 represents disks mounted upon the shaft in a relation which adapts them to aHord support to a sheet of steel or other material that is to be heat treated in the furnace. These disks areconstructed with rims- 3, webs 4: and hubs 5, according to the particular construction of disk here selected for purposes of illustration, which construction is that of copending application Serial No. 326,513, now Patent No. 1,780,018.

For purposes of illustration, the several features of the present invention are illustrated in connection with a shaft 1 which is usuall ly constructed of some suitable alloy which bestows upon it the capacity of retaining its shape when supported by its lends in external bearings as shown, and while its intermediate or body portion is subjected to the relatively high temperatures under which the furnace is worked, and which, in order that it will stand up under these conditions, has its body portion made ofrelatively large diameter, hollow, and with relatively thin walls, while the supporting ends are of materially smaller diameter and merge with the enlarged body portion after the manner of a bottle-neck; this construction being found also to reduce heat losses by conduction and convection, particularly when the shaft is of the non-cooled type. it is to be understood that the invention is applicable to shafts of other construction, and even shafts in connection with which a conduit is used for the purpose of passing a cooling medium through the shaft.

Referring to Figures 1 to 3 inclusive, shaft 1 is provided with elevations 6 adapted to receive the hubs 5 of the disks 2, seine of which elevations are provided with slots 7 extending in the direction of the axis of the shaft for the purpose of subdividing the circumference and'interrupting stresses that might otherwise be set up under high heat expansion; and these slots T may extend longitudinally beyond the elevations, if desired, to insure this effect. The elevations G arc circumferentially interrupted in order to leave between them a series of recesses 8 in the circumferential direction of the shaft, over which recesses a disk, mounted upon a given series of elevations, will remain out of contact with the shaft as a further safeguard against setting up of undesirable stresses, for instance, stresses due to resistance of the disk to circumferential expansion of the shaft.: Additionaladvantages arise from the use of elevations upon which to mount the disks, among which are greater convenience in providing dressed surfaces upon which to seat the disks, and greater convenience in moving vthe disks to their seats upon the elevations.

An important feature of the preferred embodiment 'of vthe present invention consists in developing (for instance, by appropriate shaping of the core in casting) the elevations 6 as deflectionsin the wall of the shaft, as distinguished from massive protuberances developed by mere increase of thickness of the walls where'the elevations are required and the change from one level to the other is without abrupt angle. This condition further contributes to the avoidance of undesired stresses under changes of dimension incident to changes in temperature.

Another important feature of the preferred embodiment of the present invention consists in the use of one or more of the elevations upon which a disk seats to trans-v to receive a stud 11, it is merely necessary to perforate the elevation 6a as shown at 110@ to admit the shank of said stud, in order 'to establish an eficient drive between an elevation and a disk. And in order to render convenient the assembly of the disk into such driving relation, the recess 10, as shown in Figures 3 and 5, may be of bayonet oint type and provided with a gate 12 through which the stud 11 may enter by axial relative movementl between the disk and the shaft, the gate 12, after assembly, being closed by filler pin 13 releasably held in place by slitting its end 14 after the manner of a cotter pin. rIhus, in assembling the disk with the shaft, in addition to seating the disk upon the elevations of the shaft, the driving connection between an elevation and the disk is established by merely dropping stud 11 in a recess 11x, then sliding the disk axially until the stud 11 arrives opposite the recess 10, then imparting a. slight rotary movement to the disk, and finally inserting and elinching the filler pin 13.

According to Figure e, driving interlock between the disk and the shaft is established at two diametrically opposite elevations 6a by inserting the through pin 11a in two holes 11aa and then working the bayonet joint assembly as described, the single filler pin 13 being suiiicient to prevent counter-rotation that would release the interlock.

According to Figures 6 and 7, the bayonet joint stud 15 is carried by the hub 5a of the disk 2a; and this stud, after entering a slot 7a extending through an elevation 6, may be shifted into a bayonet joint pocket 16 in said elevation, and there confined against displacement by means of a cotter pin 17 inserted into the slot 7a, so that in this instance the slotted elevation -6 becomes the driving elevation.

According to Figures 8 and 9, the slot 7 is made an element ofthe interlock by providing each disk hub 5?) with a key-lug 18 that slides into one of the slots 7 as the disk is brought to its seat, and the disks are prevented froin sliding axially out of the resultant driving interlock by means of end rings 20 secured by screws 21 and intermediate spacing strips 19, the ends of which enter the slots 7 of the elevations 6 and into abutment with the lugs 18, and are there held bythe overlapping portions of the hubs 5b so that here again the elevations serve not only as4 disk seating 4means but asl disk driving means. e

yIt is to be noted that in the form shown in Figures 6 and 7 where the bayonet joint studs are carried by the disks, as well as the form shown in Figures `8 and 9, each disk will be able to pass antecedent disks in reaching its own seat, since the driving projections which the disks carry can pass completely through a slot if necessary, or pass between two elevations until it reaches the circumferential series of elevations which are to serve as its own seat, when its driving projection will be passed into the slot which is to interlock it with its Vown driving elevation. In Figure 6 the slotted elevations will be alternated in position instead of being in alignment as in Figure 8, but it will merely be necessary, in passing one elevation to reach another, to move the disk axially until its bayonet joint stud 16 passes a slot, then rotate it until it comes opposite the next slot, and so on until it reaches its own seat.

I claim: K

1. A shaft for supporting workpieces within a heat treatment furnace, said shaft consisting of a cylindrical body portion constructed with a relatively thin wall and having upon the exterior of its wall integral seating elevations; the thickness of the wall vat such seating elevations being not materiallygreater than that of the main portion of the wall.

' 2. In combination with the shaft described in claim 1, a work-supporting disk seated upon a plurality of the elevations of said shaft, and means interconnecting said disk with at least one of said elevations and transmitting rotary drive from the shaft to the disk.

3. A hollow shaft for heat treatment furnaces, constructed with relatively thin walls and having its said walls deflected radially outward at a plurality of circumferentially spaced places providing an annular series of disk seating elevations; said walls at the places of said elevations being approximately uniform in thickness with other portions of the walls.

4. A hollow shaft for heat treatment furnaces as described in claim 3, in which the disk seating elevations are arranged in a i plurality of circumferential series, with portions of the main cylindrical surface of the shaft alternating with the elevations of each series and also with the several series of elevations.

5. A hollow shaft for heat treatment fur-l naces as described in claim 3, in which at least one of the elevations is slotted longitudinally of the shaft to receive drive-transmitting means carried by a disk.

6.A hollow shaft forheat treatment furnaces as described in claim 3, in which at least one of the elevations is slotted longitudinally of the shaft to receive drive-trans- '5 mitting means carried by a disk; said slot extending through said elevation in the direct-ion of the axis of the shaft.

7. A shaft for heat treatment furnaces as described in claim 8, in which the circumfer- '10 ential series of elevations is repeated at intervals in the axial direction of the shaft, and said shaft has mounted upon each circumferential series of elevations a sheet supporting disk; the several disks and seating elevations being constructed to permit a disk, in reaching the series of elevations upon which it is mounted, to pass the elevations of antecedent circumferential series.

8. A conveying shaft for heat treatment 2o furnaces, constructed with a relatively largediameter, thin Walled body portion, which said Wall is radially deflected to provide external surface elevations at selected positions Without materially varying the thickness of the. wall.

9. A conveying shaft for heat treatment furnaces, constructed with a relatively largedial'neter, thin Walled body portion, which said Wall is radially deiiected to provide external surface elevations at selected positionsI Without materially varying the thickness of the Wall; said elevations extending but a fraction of the vcircumferential dimensions of the shaft, and leaving relatively loW intervening portions of the shaft in circumferential series with them; said shaft also having in its Wall slots extending'at a substantial angle to its circumference; and said slots extending through said elevations.

40 Signed at Chicago, Illinois, this 24th 'day of September, 1930.

FRANK A. FAHRENWALD. 

